add down propagated data to late BrowserPropagationDataStorage

[EddeCCC]

If a BrowserPropagationDataStorage is not created in the first context, but in a later one, earlier created data, which was down propagated still has to be included into the data storage.

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This change is 

[codecov]

Codecov Report

Merging #1621 (8dc01b2) into master (a4e425a) will increase coverage by 0.05%.
Report is 1 commits behind head on master.
The diff coverage is 100.00%.

❗ Current head 8dc01b2 differs from pull request most recent head f2d4a34. Consider uploading reports for the commit f2d4a34 to get more accurate results

@@             Coverage Diff              @@
##             master    #1621      +/-   ##
============================================
+ Coverage     78.32%   78.37%   +0.05%     
- Complexity     2518     2520       +2     
============================================
  Files           257      257              
  Lines          8256     8257       +1     
  Branches        984      984              
============================================
+ Hits           6466     6471       +5     
+ Misses         1364     1358       -6     
- Partials        426      428       +2     

Files	Coverage Δ
.../instrumentation/context/InspectitContextImpl.java	91.47% <100.00%> (-0.44%)	⬇️

... and 3 files with indirect coverage changes

[TitusLabs]

Reviewed 1 of 2 files at r1, 3 of 3 files at r2, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @EddeCCC)